Bearing and lubrication system

ABSTRACT

A bearing and lubrication system for a rotatable shaft comprising a journal bearing assembly for supporting the shaft, a thrust bearing assembly for limiting axial movement of the shaft, and a ring surrounding the shaft and having a portion of the inner surface thereof drivingly engaged by the shaft wherein rotation of the shaft causes rotation of the rings. A supply of lubricant is disposed beneath the ring in the path of travel thereof as the ring rotates under the influence of the shaft, wherein rotation of the ring causes lubricant to cling thereto and be elevated thereby. A first portion of the elevated lubricant is introduced to the journal bearing assembly to lubricate surfaces thereof, and a second portion of the elevated lubricant is radially thrown outward by the ring. The bearing and lubrication system further comprises collecting troughs for collecting lubricant radially thrown outward by the ring, and a plurality of channels for conducting lubricant from the collecting troughs into the thrust bearing assembly to lubricate surfaces thereof.

DESCRIPTION BACKGROUND OF THE INVENTION

This invention relates generally to a bearing and lubrication system fora rotating shaft, and more particularly to systems of the type employingoil rings to deliver a lubricant from a supply thereof to a bearingassembly.

Rotating machinery such as gas or steam powered turbines typicallyinclude a power shaft, one or more sleeve or journal bearing assembliesto rotatably support the shaft, and one or more thrust bearingassemblies to limit axial movement of the shaft. Lubricant must besupplied to these bearing assemblies, and often the bearing assembliesof a rotating machinery are spaced from each other and a separatelubrication system is provided for each bearing assembly. Manylubrication systems are well known in the art, and one common type ofsystem includes an oil ring or rings arranged within a bearing assemblyso as to encircle the power shaft. The oil ring has a diameter greaterthan the diameter of the shaft, and the ring is positioned above a poolof lubricant so that at least a portion of the circumference of the ringis submerged within the lubricant. Rotation of the power shaft withinthe bearing assemblies causes rotation of the oil ring. As the oil ringrotates and travels through the supply of lubricant, lubricant clings tothe oil ring and is carried upward thereby. The inner surface of the oilring is usually provided with grooves or the like to increase the amountof oil which clings to the ring and is carried upward thereby. Oilcarried upward by the inner surfaces of the oil ring is deposited on andmigrates along the bearing surfaces of a bearing assembly, lubricatingthese surfaces. Oil carried upward by the outside surfaces of the oilring is thrown radially outward by the ring toward the shell or casingof the machinery, and this oil generally flows down the inside surfaceof the shell, returning to the lubricant pool.

As the lubricant flows along surfaces of the shaft and associatedbearing assemblies, the lubricant is heated by friction between thesesurfaces. Often, the lubricant is cooled by being circulated through aheat exchanger. In this case, a lubricant pump is frequently employed tocirculate the lubricant between the supply thereof and the heatexchanger. This pump and its associated piping increase the cost andcomplexity of manufacturing, operating, and maintaining the rotatablemachinery.

SUMMARY OF THE INVENTION

In light of the above, an object of this invention is to improverotating machinery, particularly bearing and lubrication systemsthereof.

Another object of the present invention is to position a thrust bearingassembly within a journal bearing assembly and employ a common set ofoil rings to lubricate both bearing assemblies.

A further object of this invention is to lubricate a thrust bearingassembly with lubricant thrown off an oil ring.

Still another object of the present invention is to collect lubricantthrown off an oil ring and direct the lubricant to surfaces of a thrustbearing assembly.

These and other objectives are attained with a bearing and lubricationsystem for a rotatable shaft comprising a journal bearing assembly forsupporting the shaft, a thrust bearing assembly for limiting axialmovement of the shaft, and a ring surrounding the shaft and having aportion of the inner surface thereof drivingly engaged by the shaftwherein rotation of the shaft causes rotation of the ring. A supply oflubricant is disposed beneath the ring in the path of travel thereof asthe ring rotates under the influence of the shaft, wherein rotation ofthe ring causes lubricant to cling thereto and be elevated thereby. Afirst portion of the elevated lubricant is introduced to the journalbearing assembly to lubricate surfaces thereof, and a second portion ofthe elevated lubricant is radially thrown outward by the ring. Thebearing and lubrication system further comprises trough means forcollecting lubricant radially thrown outward by the ring, and conduitmeans for conducting lubricant from the trough means into the thrustbearing assembly to lubricate surfaces thereof.

A BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view, partly in cross-section, of portions of arotating machine employing the bearing and lubrication system of thepresent invention;

FIG. 2 is a front cross-sectional view taken along line II--II of FIG. 1with portions of the thrust collar removed; and

FIG. 3 is a top cross-sectional view taken along line III--III of FIG.2.

A DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Machinery of the type to which the bearing and lubrication systemforming the subject of the present invention may be applied isillustrated in part in FIG. 1. Power shaft 10 of a machine such as aturbine is shown arranged within casing or housing 12 of the turbine.Housing 12 includes journal bearing assembly 14 for rotatably supportingshaft 10, and thrust bearing assembly 16 for limiting axial movement ofthe shaft. As is conventional in machinery of a type underconsideration, the parts described above with the exception of powershaft 10 are formed in two halves, an upper and lower half, andthereafter united.

Journal bearing assembly 14 includes upper bearing retainer 18, lowerbearing retainer 20, and sleeves 22. Retainers 18 and 20 are fixedrelative to housing 12 and may be formed integrally therewith. Retainers18 and 20 encircle power shaft 10, and sleeves 22 are disposed betweenthe bearing retainers and the power shaft. Shaft 10 is supported by andis free to rotate within bearing sleeves 22; and the bearing sleeves, inturn, are supported by and are free to rotate within retainers 18 and20. Stops (not shown) may be provided to limit axial movement of bearingsleeves 22. A thin film of lubricant (not shown) is maintained betweenadjacent surfaces of shaft 10, retainers 18 and 20, and sleeves 22,lubricating these surfaces.

Thrust bearing assembly 16 includes thrust collar 24, front thrust plate26, back thrust plate 28, and lateral cavity 30 which is defined bysurfaces of bearing retainers 18 and 20. Collar 24 is fixed to androtates with power shaft 10, and the collar radially extends outwardfrom the shaft into cavity 30. Thrust plates 26 and 28 are ring-shapedand are positioned within cavity 30, radially spaced from and encirclingshaft 10. Preferably there is a close radial fit between plates 26 and28 and bearing retainers 18 and 20 to limit radial movement of theplates. Front thrust plate 26 is axially positioned between a front sideof the thrust collar 24 and the surfaces of bearing retainers 18 and 20defining lateral cavity 30, and back thrust plate 28 is axiallypositioned between a back side of the thrust collar and the surfaces ofthe bearing retainers defining the lateral cavity. Plates 26 and 28 arefree to rotate within cavity 30, but retainers 18 and 20 limit axialmovement of the thrust plates. Similarly, collar 24 is free to rotatewithin cavity 30 between plates 26 and 28, but the plates limit axialmovement of the thrust collar and, hence, power shaft 10. A thin film oflubricant (not shown) is maintained between adjacent surfaces ofretainers 18 and 20, collar 24, and plates 26 and 28, lubricating thesesurfaces.

Particularly referring to FIG. 1, each bearing sleeve 22 defines acircumferentially extending notch or slot 32, and oil ring 34 is mountedon and drivingly engaged by shaft 10 between the axial edges of eachnotch 32. Oil rings 34 have a diameter greater than the diameter ofpower shaft 10, and the oil rings encircle the power shaft. With thisarrangement, rotation of power shaft 10 causes rotation of oil rings 34,with the oil rings rotating at a slower rate than the power shaft. Apool or supply of lubricant 36 is disposed within casing 12 beneath oilrings 34 in the path of travel thereof as the oil rings rotate under theinfluence of shaft 10. As oil rings 34 rotate, lubricant clings theretoand is elevated thereby, and the inner surfaces of the oil rings may beprovided with grooves (not shown) to facilitate lifting lubricant fromsupply 36.

A first portion of a lubricant raised by oil rings 34, primarily thelubricant carried upwards by the inner surfaces of the oil rings, isdeposited on surfaces of shaft 10 and bearing sleeves 22. The lubricantaxially migrates along these surfaces, providing the thin film oflubricant between adjacent surfaces of shaft 10, bearing retainers 18and 20, and bearing sleeves 22. Eventually, the lubricant axiallymigrates across the bearing surfaces of journal bearing assembly 14 andreturns to supply 36. A second portion of the lubricant carried upwardby oil rings 34, specifically lubricant carried upward by outer surfacesof the oil rings, is radially thrown outward by the rings under theaction of centrifugal force.

The system of the present invention comprises trough means forcollecting lubricant radially thrown outward by oil rings 34, andconduit means for conducting lubricant from the trough means into thrustbearing assembly 16 to lubricate surfaces thereof. Preferably, as shownin FIGS. 2 and 3, the trough means includes a plurality of collectiontroughs 38 secured to casing 12 on either side of shaft 10. The conduitmeans includes, in the preferred arrangement, a pair of front channelmeans 42 and a pair of back channel means 44, wherein one front channelmeans and one back channel means is located on each side of power shaft10.

Channel means 42 and 44 guide lubricant from collecting troughs 38 intolateral cavity 30. More specifically, front channel means 42 guideslubricant into the area radially below shaft 10 and inside front thrustplate 26 and axially between thrust collar 24 and lower bearing retainer20. Analogously, back channel means 44 guides lubricant into the arearadially below shaft 10 and inside back thrust plate 28 and axiallybetween thrust collar 24 and lower bearing retainer 20. The lubricantintroduced into thrust bearing assembly 16 by first and second channelmeans 42 and 44 radially and circumferentially migrates along surfacesof bearing retainers 18 and 20, thrust collar 24 and thrust plates 24and 26, lubricating these surfaces. The migration of the lubricant alongthe surfaces of thrust bearing assembly 16 is assisted by the relativemotion between bearing retainers 18 and 20, thrust collar 24, and thrustplates 26 and 28 and by a plurality of circumferentially equally spacedradial grooves 46 (shown only in FIG. 2) defined by the surfaces ofthrust plates 26 and 28 adjacent to the thrust collar.

Thus, it can be seen that the present invention utilizes lubricantradially thrown off oil rings 34, which, with prior art arrangements,normally returns directly to lubricant supply 36, to lubricate thrustbearing assembly 16 and, in this manner, provides a single lubricationsystem to lubricate both journal bearing assembly 14 and thrust bearingassembly 16. The necessity for a separate lubrication system for eachbearing assembly is eliminated, reducing the cost of and simplifying theconstruction, operation, and maintenance of the rotatable machine.

Preferably, upper bearing retainer 18 includes upper sleeve member 48and lower bearing retainer 20 includes lower sleeve member 50. Sleevemembers 48 and 50 annularly encircle thrust plates 26 and 28 and thrustcollar 24. Sleeve members 48 and 50 are in a close radial fit withthrust plates 26 and 28 throughout the circumference thereof, but sleevemembers 48 and 50 are radially spaced from the thrust collar. With thisarrangement, sleeve members 48 and 50, thrust plates 26 and 28 andthrust collar 24 define annular chamber 52. As lubricant migrates acrosssurfaces of thrust collar 24 and reaches the outside surface thereof,the lubricant is radially thrown outward by the thrust collar intochamber 52 under the action of centrifugal force. Referring to FIG. 2,aperture 54 is provided in lower sleeve member 50 for passing lubricantfrom annular chamber 52 and through the lower sleeve member forreturning the lubricant to supply 36.

The centrifugal force applied to the lubricant by thrust collar 24increases the pressure of the lubricant in chamber 52. This increasedpressure may be employed to circulate the lubricant between thrustbearing assembly 16 and a remote location without the need for aseparate lubricant pump and its associated costs of manufacture,operation, and maintenance. For example, the lubricant can be circulatedto another bearing assembly or an external piece of machinery. Forexample, referring to FIG. 2, the lubricant may be circulated throughoil filter 56 and oil cooler 58, and back to supply 36 via oil line 60.

While it is apparent that the invention herein disclosed is wellcalculated to fulfill the objects above-stated, it will be appreciatedthat numerous modifications and embodiments may be devised by thoseskilled in the art, and it is intended that the appended claims coverall such modifications and embodiments as fall within the true spiritand scope of the present invention.

I claim:
 1. A bearing and lubrication system for a rotatable shaftcomprising:a journal bearing assembly for supporting the shaft; a thrustbearing assembly for limiting axial movement of the shaft and includinga cavity defined by surfaces of the journal bearing assembly, a thrustcollar supported by the shaft and radially extending outward therefrominto the cavity, and thrust plate means positioned within the cavitybetween the thrust collar and the surfaces of the journal bearingassembly defining the cavity, and radially spaced from the shaft; a ringsurrounding the shaft and having a portion of the inner surface thereofdrivingly engaged by the shaft wherein rotation of the shaft causesrotation of the ring; a supply of lubricant disposed beneath the ring inthe path of travel thereof as the ring rotates under the influence ofthe shaft, wherein rotation of the ring causes lubricant to clingthereto and be elevated thereby, and wherein a first portion of theelevated lubricant is introduced to the journal bearing assembly tolubricate surfaces thereof and a second portion of the elevatedlubricant is radially thrown outward by the ring; and trough means forcollecting lubricant radially thrown outward by the ring; and conduitmeans for conducting lubricant from the trough means into the thrustbearing assembly to lubricate surfaces thereof and including channelmeans for guiding lubricant from the trough means and into the arearadially between the shaft and the thrust plate means and axiallybetween the thrust collar and the surfaces of the journal bearingassembly defining the cavity.
 2. The bearing and lubrication system ofclaim 1 further including:a sleeve member annularly encircling thethrust plate means and the thrust collar, the sleeve member radiallybeing in a close fitting relationship with the thrust plate means andradially being spaced from the thrust collar wherein the annular member,the thrust plate means, and the thrust collar define an annular chamber;and aperture means for passing lubricant from the annular chamber andthrough the sleeve member for returning the lubricant to the supplythereof.
 3. The bearing and lubrication system of claim 2wherein:lubricant introduced into the thrust bearing assembly radiallymigrates along surfaces of the thrust collar and is radially thrownoutward thereby into the annular chamber, increasing the pressure of thelubricant; and further including means for circulating the pressurizedlubricant to a remote location.
 4. The bearing and lubrication system ofclaim 3 wherein the oil ring is positioned within the journal bearingassembly.
 5. The bearing and lubrication system of claims 1, 2, 3 or 4wherein:the thrust plate means includes a front thrust plate positionedwithin the cavity between a front side of the thrust collar and thesurfaces of the journal bearing assembly defining the cavity, whereinthe front thrust plate is radially spaced from the shaft, and a backthrust plate positioned within the cavity between a back side of thethrust collar and the surfaces of the journal bearing assembly definingthe cavity, wherein the back thrust plate is radially spaced from theshaft; and the channel means includes front channel means for guidinglubricant from the trough means and into the area radially between theshaft and the front thrust plate and axially between the thrust collarand the surfaces of the journal bearing assembly defining the cavity,and back channel means for guiding lubricant from the trough means andinto the area radially between the shaft and the back thrust plate andaxially between the thrust collar and the surfaces of the journalbearing assembly defining the cavity.